Correct Answer: B

Rationale: Laser light differs from typical light sources due to its monochromatic nature (single color) and coherence (synchronized waves). This means that laser light consists of a single wavelength and synchronized waves, unlike typical light sources that emit a range of wavelengths and are incoherent. The monochromatic nature of laser light allows it to be of a single color, while coherence ensures that the waves are synchronized. These unique properties of laser light make it valuable for a wide range of applications in fields such as medicine, industry, and research. Choices A, C, and D are incorrect because laser light's distinguishing features are not related to enhanced brightness, increased velocity, or limited visibility to the human eye. Instead, it is the monochromatic nature and coherence that set laser light apart from typical light sources.

Correct Answer: C

Rationale: Vitamin D is essential for calcium absorption in the intestines, which is crucial for maintaining strong and healthy bones. Without adequate vitamin D, the body cannot effectively absorb calcium, leading to weakened bones and an increased risk of fractures. Vitamin A (Choice A) is important for vision and immune function but is not directly involved in calcium absorption or bone health. Vitamin C (Choice B) is essential for collagen synthesis and immune function, but it does not play a direct role in calcium absorption or bone health. Vitamin E (Choice D) acts as an antioxidant and helps protect cells from damage, but it is not specifically required for calcium absorption or bone health. Therefore, the correct answer is Vitamin D as it is crucial for optimal bone health.

Correct Answer: B

Rationale: The circulatory system, comprising the heart, blood vessels (arteries, veins, and capillaries), and blood, is responsible for transporting blood, oxygen, nutrients, and waste products throughout the body. The lymphatic system aids in maintaining fluid balance and fighting infections; the nervous system transmits signals. The respiratory system facilitates the exchange of oxygen and carbon dioxide in the body, which is distinct from the circulatory system's role in blood transport. Therefore, the correct answer is the Circulatory system (Choice B). Choices A, C, and D are incorrect as they do not pertain to the intricate network of blood vessels responsible for transporting blood throughout the body.

Correct Answer: B

Rationale: Demyelination specifically refers to the degeneration of the myelin sheath that covers nerve fibers. When demyelination occurs, nerve function and communication can be impaired. Potentiation involves the strengthening of synaptic connections, reuptake is the reabsorption process of neurotransmitters by the presynaptic neuron, and neurogenesis is the generation of new neurons. Therefore, the correct term for the degeneration of nerve tissue among the options provided is demyelination.

Correct Answer: B

Rationale: Pernicious anemia is caused by a deficiency in vitamin B12 (cobalamin). Vitamin B12 is essential for the production of red blood cells and for the proper functioning of the nervous system. Pernicious anemia occurs when there is a lack of intrinsic factor, a protein produced in the stomach that is necessary for the absorption of vitamin B12 in the digestive system. Vitamin A, Vitamin D, and Vitamin E deficiencies do not lead to pernicious anemia. Vitamin A deficiency can cause night blindness and skin issues, Vitamin D deficiency can lead to rickets or osteomalacia, and Vitamin E deficiency can result in neurological problems and muscle weakness.